Novel XLRS1 gene mutations cause X-linked juvenile retinoschisis in Chinese families

Birt-Hogg-Dube syndrome (BHD, OMIM#135150) is a rare disease in clinic; it is characterized by skin fibrofolliculomas, pulmonary cysts with an increased risk of recurrent pneumothorax, renal cysts, and renal neoplasms. Previous studies have demonstrated that variants in folliculin (FLCN, NM_144997) are mainly responsible for this disease. In this research, we enrolled two BHD families and applied direct sequencing of FLCN to explore the genetic lesions in them. Two FLCN mutations were identified: one is a novel deletion variant (c.668delA/p.N223TfsX19), while the other is a previously reported insertion mutation (c.1579_1580insA/p.R527QfsX75). And the pathogenicity of both variants was confirmed by cosegregation assay. Bioinformatics analysis showed that c.668delA may lead to functional haploinsufficiency of FLCN because mRNA carrying this mutation exhibits a faster degradation rate comparing to the wild type. Real-time qPCR also confirmed that the mRNA level of FLCN expression in the proband was decreased significantly compared with the controls, which may disrupt the mTOR pathway and lead to BHD. The insertion mutation (c.1579_1580insA) was predicted to cause a prolonged amino acid sequence of FLCN. The present identification of two mutations not only further supports the important role of tumor suppressor FLCN in BHD and primary spontaneous pneumothorax, but also expands the spectrum of FLCN mutations and will provide insight into genetic diagnosis and counseling of families with BHD.

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Genetic investigation of 211 Chinese families expands the mutational and phenotypical spectrum in hereditary retinopathy genes through targeted sequencing technology

10.21203/rs.3.rs-20958/v2 ◽

2020 ◽

Author(s):

Zhouxian Bai ◽

Yanchuan Xie ◽

Lina Liu ◽

Jingzhi Shao ◽

Yuying Liu ◽

...

Keyword(s):

Sanger Sequencing ◽

Molecular Genetic ◽

Gene Mutations ◽

Central China ◽

Disease Genes ◽

Sequencing Data ◽

Chinese Families ◽

Targeted Next Generation Sequencing ◽

Ophthalmologic Examination ◽

Generation Sequencing

Abstract Background: Hereditary retinopathy is a significant cause of blindness worldwide. Despite the discovery of many mutations in various retinopathies, a large part of patients remain undiagnosed genetically. Targeted next generation sequencing of the human genome is a suitable approach for retinopathy molecular diagnosis.Methods: We described a cohort of 211 families from central China with various forms of retinopathy, 95 families of which were investigated using NGS multi-gene panel sequencing as well as the other 116 patients were LHON suspected tested by Sanger sequencing. We validated the candidate variants by PCR-based Sanger sequencing. We have made comprehensive analysis of the cases through sequencing data and ophthalmologic examination information.Results: The potentially causal mutation was identified in majority of the families with retinopathy (57.9% of 95 families) and Leber hereditary optic neuropathy (LHON) (21.6% of 116 families). The identified mutations (68mutations, 37 of which are novel) of the 95 families spanned 31 known disease genes, about half have not been reported relation to hereditary retinopathy. The NGS panel solution provides 45.3% potential diagnostic rate of the retinopathy families and another 12.6% families detect candidate gene mutations with undefined pathogenicity in this study.Conclusion: Our study showed novel mutations and phenotypic aspects of retinopathy, and demonstrated genetic and clinical heterogeneity of the conditions. Our results illustrated the significance of molecular genetic testing for patients with hereditary retinopathy.

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